CVE-2020-9395 in RTL8195AM
Summary
by MITRE
An issue was discovered on Realtek RTL8195AM, RTL8711AM, RTL8711AF, and RTL8710AF devices before 2.0.6. A stack-based buffer overflow exists in the client code that takes care of WPA2's 4-way-handshake via a malformed EAPOL-Key packet with a long keydata buffer.
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Analysis
by VulDB Data Team • 07/07/2020
The vulnerability identified as CVE-2020-9395 represents a critical stack-based buffer overflow flaw affecting Realtek wireless networking devices including the RTL8195AM, RTL8711AM, RTL8711AF, and RTL8710AF chipsets. This vulnerability exists in the client-side implementation responsible for handling WPA2 4-way handshake processes, specifically when processing EAPOL-Key packets containing excessively long keydata buffers. The flaw resides in the firmware level implementation of wireless security protocols, making it particularly dangerous as it can be exploited during normal wireless network authentication procedures.
The technical exploitation of this vulnerability occurs through the manipulation of EAPOL-Key packets during the WPA2 authentication process, where an attacker can craft malformed packets containing oversized keydata fields that exceed the allocated buffer space within the device's memory. This buffer overflow condition allows for arbitrary code execution or system crashes, potentially leading to complete device compromise. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, where insufficient bounds checking permits data to overwrite adjacent memory locations. The attack vector requires the target device to be within range of the malicious wireless network and to attempt authentication with the crafted packet, making it particularly concerning for wireless infrastructure security.
The operational impact of CVE-2020-9395 extends beyond simple device instability, as it can lead to complete network compromise when exploited. Attackers can leverage this vulnerability to gain persistent access to wireless networks, potentially enabling man-in-the-middle attacks, data interception, or further network penetration. The affected devices operate at the edge of wireless infrastructure, making them attractive targets for attackers seeking to establish footholds within corporate or residential networks. This vulnerability specifically impacts the WPA2 security framework's integrity, undermining the fundamental security assumptions of wireless authentication protocols. The issue affects devices running firmware versions prior to 2.0.6, indicating that the vulnerability has existed for an extended period without proper mitigation.
Mitigation strategies for CVE-2020-9395 primarily involve firmware updates from Realtek to address the buffer overflow condition in the WPA2 implementation. Network administrators should prioritize updating all affected devices to firmware version 2.0.6 or later, as this represents the official patch for the vulnerability. Additional defensive measures include implementing network monitoring to detect malformed EAPOL-Key packets, configuring wireless access points to disable vulnerable authentication methods, and employing intrusion detection systems that can identify suspicious wireless traffic patterns. The vulnerability aligns with ATT&CK technique T1046 which involves network service scanning, and T1566 which covers credential access through social engineering, as attackers may use this vulnerability to gain unauthorized access to wireless networks. Organizations should also consider implementing network segmentation to limit the potential impact of exploitation and establish robust wireless security policies that include regular firmware updates and vulnerability assessments.